A recent type of magnetic disk apparatus has a design based on what is called the Winchester technique. A magnetic disk starts rotating in a state of being in contact with the magnetic head. As the rotational speed of the magnetic disk on which magnetic head slides increases, the magnetic head rises due to the air stream induced between the magnetic head and the magnetic disk. The recording and reproducing operations are executed with the magnetic head in such a floating state. When the rotation of the magnetic disk stops, the magnetic head again rests on the surface of the magnetic disk. Such an operation of the magnetic head is generally called a contact-start-stop (abbreviated to CSS) operation. Such this CSS operation represents a kind of abrasion phenomenon, the characteristics of the magnetic head and magnetic disk deteriorate with any increase in rotational speed. There is a particularly remarkable tendency for the coefficient of abrasion between the magnetic head and the magnetic disk to gradually increase, and there may be a case where the friction coefficient exceeds "1". Such a state is called an adsoption state. When this adsorption state occurs, the load torque of the motor which drives the magnetic disk is larger than the starting torque thereof, so that not only is a starting error caused but also excessive force is applied to the magnetic head and magnetic disk system, causing certain parts to be broken.
Since no active countermeasures are taken against the adsorption phenomenon in regard to the magnetic head of a conventional magnetic disk apparatus of this type, there is a significant deficiency in reliability.